NEW YORK — The overnight police raids in Philadelphia and Los Angeles that dismantled two of the nation's biggest Occupy Wall Street encampments leave just a few major "occupations" still going on around the country. But activists are already changing tactics and warning of a winter of discontent, with rallies and marches every week.

The camps may bloom again in the spring, organizers said, and next summer could bring huge demonstrations at the Republican and Democratic conventions, in Tampa and Charlotte, N.C., respectively, when the whole world is watching. But for now they are promoting dozens of smaller actions, such as picketing the president in New York and staging sit-ins at homes marked for foreclosure.

"We intend to use this for what it is — basically six months to get our feet underneath us, to get strong," said Phil Striegel, a community activist in San Francisco.

On Wednesday, masked sanitation workers hauled away 25 tons of debris from the lawns around Los Angeles City Hall after police raided the protesters' camp in the middle of the night and arrested more than 300 people. Mayor Antonio Villaraigosa said it would cost about $1 million to clean up the site. In Philadelphia, dozens of police patrolled a plaza outside City Hall after sweeping it of demonstrators and arresting 50.

In the past few weeks, police broke up encampments in such cities as Portland, Ore., Oakland, Calif., and New York, where the sit-down protests against social inequality and corporate excesses began in mid September. Protesters are still at it in places like Boston and Washington, which each had camps of about 100 tents Wednesday.

While some observers wondered whether the movement would wither without ground on which to make its stand, many protesters refused to concede defeat.

Protesters in Philadelphia marched from the city's well-to-do Rittenhouse Square to police headquarters Wednesday afternoon and called for a "victory march" for Friday or Saturday.

In New York, protesters have continued to meet in Zuccotti Park, where the Occupy movement began, even though police cleared out their tents Nov. 15. They planned to protest outside a fundraising dinner by President Barack Obama on Wednesday and a conference of aerospace executives today that they branded a meeting of "war profiteers."